The patch titled
Subject: poweroff: change orderly_poweroff() to use schedule_work()
has been added to the -mm tree. Its filename is
poweroff-change-orderly_poweroff-to-use-schedule_work.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: poweroff: change orderly_poweroff() to use schedule_work()
David said:
Commit 6c0c0d4d108 ("poweroff: fix bug in orderly_poweroff()")
apparently fixes one bug in orderly_poweroff(), but introduces
another. The comments on orderly_poweroff() claim it can be called
from any context - and indeed we call it from interrupt context in
arch/powerpc/platforms/pseries/ras.c for example. But since that
commit this is no longer safe, since call_usermodehelper_fns() is not
safe in interrupt context without the UMH_NO_WAIT option.
orderly_poweroff() can be used from any context but UMH_WAIT_EXEC is
sleepable. Move the "force" logic into __orderly_poweroff() and change
orderly_poweroff() to use the global poweroff_work which simply calls
__orderly_poweroff().
While at it, remove the unneeded "int argc" and change argv_split() to use
GFP_KERNEL.
We use the global "bool poweroff_force" to pass the argument, this can
obviously affect the previous request if it is pending/running. So we
only allow the "false => true" transition assuming that the pending "true"
should succeed anyway. If schedule_work() fails after that we know that
work->func() was not called yet, it must see the new value.
This means that orderly_poweroff() becomes async even if we do not run the
command and always succeeds, schedule_work() can only fail if the work is
already pending. We can export __orderly_poweroff() and change the
non-atomic callers which want the old semantics.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Reported-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Reported-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Feng Hong <hongfeng@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 57 +++++++++++++++++++++++++++----------------------
1 file changed, 32 insertions(+), 25 deletions(-)
diff -puN kernel/sys.c~poweroff-change-orderly_poweroff-to-use-schedule_work kernel/sys.c
--- a/kernel/sys.c~poweroff-change-orderly_poweroff-to-use-schedule_work
+++ a/kernel/sys.c
@@ -2199,9 +2199,8 @@ SYSCALL_DEFINE3(getcpu, unsigned __user
char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
-static int __orderly_poweroff(void)
+static int __orderly_poweroff(bool force)
{
- int argc;
char **argv;
static char *envp[] = {
"HOME=/",
@@ -2210,20 +2209,40 @@ static int __orderly_poweroff(void)
};
int ret;
- argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
- if (argv == NULL) {
+ argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL);
+ if (argv) {
+ ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+ argv_free(argv);
+ } else {
printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
- __func__, poweroff_cmd);
- return -ENOMEM;
+ __func__, poweroff_cmd);
+ ret = -ENOMEM;
}
- ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_WAIT_EXEC,
- NULL, NULL, NULL);
- argv_free(argv);
+ if (ret && force) {
+ printk(KERN_WARNING "Failed to start orderly shutdown: "
+ "forcing the issue\n");
+ /*
+ * I guess this should try to kick off some daemon to sync and
+ * poweroff asap. Or not even bother syncing if we're doing an
+ * emergency shutdown?
+ */
+ emergency_sync();
+ kernel_power_off();
+ }
return ret;
}
+static bool poweroff_force;
+
+static void poweroff_work_func(struct work_struct *work)
+{
+ __orderly_poweroff(poweroff_force);
+}
+
+static DECLARE_WORK(poweroff_work, poweroff_work_func);
+
/**
* orderly_poweroff - Trigger an orderly system poweroff
* @force: force poweroff if command execution fails
@@ -2233,21 +2252,9 @@ static int __orderly_poweroff(void)
*/
int orderly_poweroff(bool force)
{
- int ret = __orderly_poweroff();
-
- if (ret && force) {
- printk(KERN_WARNING "Failed to start orderly shutdown: "
- "forcing the issue\n");
-
- /*
- * I guess this should try to kick off some daemon to sync and
- * poweroff asap. Or not even bother syncing if we're doing an
- * emergency shutdown?
- */
- emergency_sync();
- kernel_power_off();
- }
-
- return ret;
+ if (force) /* do not override the pending "true" */
+ poweroff_force = true;
+ schedule_work(&poweroff_work);
+ return 0;
}
EXPORT_SYMBOL_GPL(orderly_poweroff);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
poweroff-change-orderly_poweroff-to-use-schedule_work.patch
thinkpad-acpi-kill-hotkey_thread_mutex.patch
kthread-introduce-to_live_kthread.patch
kthread-kill-task_get_live_kthread.patch
lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch
lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch
epoll-use-rcu-to-protect-wakeup_source-in-epitem.patch
ptrace-add-ability-to-retrieve-signals-without-removing-from-a-queue-v4.patch
selftest-add-a-test-case-for-ptrace_peeksiginfo.patch
kernel-sysc-use-the-simpler-call_usermodehelper.patch
usermodehelper-export-_exec-and-_setup-functions.patch
usermodehelper-export-_exec-and-_setup-functions-fix.patch
kmod-split-call-to-call_usermodehelper_fns.patch
keys-split-call-to-call_usermodehelper_fns.patch
coredump-remove-trailling-whitespaces.patch
split-remaining-calls-to-call_usermodehelper_fns.patch
kmod-remove-call_usermodehelper_fns.patch
coredump-only-sigkill-should-interrupt-the-coredumping-task.patch
coredump-ensure-that-sigkill-always-kills-the-dumping-thread.patch
coredump-sanitize-the-setting-of-signal-group_exit_code.patch
coredump-introduce-dump_interrupted.patch
coredump-factor-out-the-setting-of-pf_dumpcore.patch
coredump-change-wait_for_dump_helpers-to-use-wait_event_interruptible.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
